1. Field of the Invention
This invention relates to a blade for liquid friction couplings, which blade consists of a disk formed with slot- or holelike apertures.
2. Description of the Prior Art
Apertures formed in the blades of liquid friction couplings will increase the torque which can be transmitted by the coupling. Said apertures consist in most cases of slots which are open at the rim of the disk. Published German Application No. 37 21 623 discloses such a disk in which the apertures have smooth longitudinal edges and the boundary surfaces of the apertures extend in planes which are normal to the surfaces of the disk. In accordance with Published German Application No. 36 27 504 the disks are formed with thicker portions at the longitudinal edges of the slot in order to promote the occurrence of mixed friction (liquid-solid friction) in the liquid friction coupling. By such thicker portions and by burrs formed during the punching or milling operations by which the apertures have been made the film that has been formed by the viscous liquid contained in the coupling is to be scraped from the adjacent blade so that the desired operating condition of mixed friction can be more easily achieved. On the other hand, said protruding thicker portions and burrs will apply a higher pressure per unit of area on the adjacent blade so that the blades will be more easily worn. If the blades are not provided with such protruding portions, the mixed friction will be less effective and the cooperation of the adjacent blades will be adversely affected so that only few blades will actually be available for a transmission of torque and those blades will be excessively loaded and be subjected to a relatively high wear.